An inductor is a common device in an electronic circuit, and a spiral inductor used in a semiconductor Integrated Circuit (IC) or in a printed circuit board (PCB) comprises at least a winding of conductive wires. Along with development of the integrated circuit technology, the inductive devices are generally prepared by adopting one conductive layer or a plurality of conductive layers. Because a winding using one conductive layer ordinarily occupies a large chip area, a winding using the plurality of conductive layers can be applied in designing an inductive device. However, inductive devices based on a winding using the plurality of conductive layers reveal some critical shortcomings with regards to the self-resonance frequency and the Q-factor.
Conventional spiral stacked inductor winding includes a single or a plurality of conductive loops forming a shape of a coil disposed in a multi-layer structure. In the multi-layer structure, each layer generally includes at least one loop. Generally, the plurality of loops of each layer is electrically connected to an underpass contact through a metal filled vias in the insulating layer.
However, generally, in the multi-layer spiral inductor winding, as shown in FIG. 4, the upper and lower nested conductive spiral layers are aligned with each other, and the nested conductive spiral loops disposed on each layer is continuous. The conductive loop on the upper layer is electrically connected to the conductive loop on the lower layer using metal filled vias. Two terminal electrodes are respectively located at the endpoints of the outer loops of the upper and lower layers, thereby may affecting the performance of the inductor such as the self-resonance frequency and the Q-factor.